1. Field of the Invention
The present invention relates to a planetary gear system, and more particularly, to a planetary gear system utilized in gas turbine engines.
2. Description of the Prior Art
In the field of propeller-gas turbine powered aircraft and specifically where two or more engines are utilized, it is desirable on some aircraft to have the propellers on either side of the fuselage rotate in opposite directions. Since the turbine engine has a standard rotational direction, it is necessary for those applications to provide different reduction gear transmissions to a given pair of gas turbine engines utilized on the same aircraft. This often means that the turbine engine having a reverse transmission may carry a gear case which is heavier than the standard rotation transmission on the other engine. Furthermore, the gear ratios are usually different and, therefore, the speed of rotation of each engine is different. Since the transmission of each engine in a pair on one aircraft is of different design, the reliability of the transmissions may be different, requiring different parts, etc.
As can be seen, the necessity of having standard rotation and reverse rotation transmissions utilized on identical engines for powering the propellers on a single aircraft, requires substantial inventory since the transmissions are meant to be assembled at the manufacturer's plant rather than in the field.
Furthermore, on each aircraft the various engines must be regulated independently in the light of the difference in weight and sometimes different r.p.m. of the propellers due to the different transmissions.